CE08 - Matériaux métalliques et inorganiques et procédés associés

Non-linear acoustical metamaterials with dynamic wave propagation control by modification of electrical conditions – MEANDRE

Electrically controlled acoustical metamaterials

Nonlinear acoustic metamaterials with dynamical wave propagation control by modification of electrical conditions

Project goals

The main objective of the project is to demonstrate experimentally the possibility to dynamically control elastic wave propagation and to study the related physical effects. For this, an adapted generic system must be designed, fabricated and exploited. This generic system is a piezoelectric phononic crystal exploiting the electric charge band gap effect, modulated in time through the dynamical control of the electrical conditions on its electrodes. In practice, two interdependent objectives are pursued:<br />1) Study the various nonlinear physical effects present in this type of system, non only by means of analytical and numerical models, but also experimentally.<br />2) Identify and study the command laws enabling the realization of functions with important potential applications, such as non-reciprocity and unidirectional transfer of energy, frequency transposition, controlled amplification, etc.

The MEANDRE project exploits some results from the ANR MIRAGE project, of which one of the objectives was the realization of tunable electric charge band gap phononic crystals, by means of the static control of their electrical conditions. At the end of the project, the first numerical studies taking into account dynamical control laws had been conducted. They showed the existence of an effect analogous to Brillouin scattering in cases where a periodic subset of grounded electrodes was shifted as a function of time. This effect is accompanied by a frequency shift of the Bragg band gaps which depends on the propagation direction. Thus, a strongly non-reciprocal behavior is expected for the transmission coefficient in specific frequency ranges, with contrasts reaching 30 dB between the passing and blocking directions for about fifteen cells. This non-reciprocity is also easily tunable, since the frequency shift of the band gaps is directly related to the shift velocity of the electrical grounds. Additionally, the study of the transmission of wave packets in the strongly non-reciprocal frequency range has shown that low signal distortion effects can be expected for this type of system.

Following the first steps of the project, a piezoelectric phononic crystal has been fabricated, in the form of a stack of rings separated by metallic electrodes. An analysis of the propagation of longitudinal acoustic waves propagating through the system has shown good agreement with the preliminary simulations. The dynamical control system of the electrical conditions is currently being finalized and will be soon connected to the stack.

The application prospects for the MEANDRE project concern firstly the development of acoustic wave-based components with novel functions. Indeed, even if the studied structures are at the meter scale, the underlying concepts can be translated to the micromectric scale for the realization of bulk or surface acoustic wave (BAW or SAW) devices for radiofrequency applications. The targeted applications in the linear case concern mainly tunable filters, widely used in reception/transmission chains. The studies conducted in this project allow to consider the development of strongly non-linear acoustic components for these chains, such as circulators or frequency transposition devices. Part of the results of the project could also be exploited to design controllable piezoelectric metamaterials to be integrated in haptic devices. Moreover, the system studied in this project could find applications in the domains of active vibration control and energy harvesting.

An oral communication about the first results of the project will be given in the frame of the e-Forum Acusticum 2020.

The objective of the projet is to design and fabricate acoustic metamaterials based on arrays of piezoelectric elements equipped with electrodes, which behavior is made strongly non-linear by introducing electronic circuits on these electrodes. Time-dependent circuits are more particularly studied. The project includes analytical model development tasks, numerical simulations (using 1D finite difference time domain as well as 3D finite element codes, and a circuit-type simulator), and experimental realizations at the metric scale (with centimetric elements). In practice, the project aims to fabricate a single piezoelectric crystal and couple it to electronic circuits of increasing complexity, ranging from simple spatio-temporally modulated connections to the electrical mass, to non-linear circuits including feedback loops. Several functions are targeted, with applications in vibration control (unidirectional transfer of vibrational energy) and for the design of non-linear acoustic wave-based components (frequency converters, circulators...). Moreover, the designed systems allow studying more complex non-linear acoustical phenomena, such as parametric amplification and absolute instabilities.

Project coordination

Charles Croënne (Institut d'électronique, de microélectronique et de nanotechnologie)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

IEMN Institut d'électronique, de microélectronique et de nanotechnologie

Help of the ANR 191,808 euros
Beginning and duration of the scientific project: December 2018 - 42 Months

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